Winding wire for an open face roll



May 20, 1969 w. s. JOHNSTON WINDING WIRE FOR AN OPEN FACE ROLL Filed Dec. 14, 1964 INVENTOR ATTORNEY United States Patent 3,445,332 WINDING WIRE FOR AN OPEN FACE ROLL William S. Johnston, 752 Lake Crest Drive, Menasha, Wis. 54952 Filed Dec. 14, 1964, Ser. No. 418,005 Int. Cl. D21f N60 US. Cl. 162-357 1 Claim ABSTRACT OF THE DISCLOSURE The woven wire facing of a dandy roll for a papermaking machine is supported on a skeleton having trunnions at opposite ends joined together by a helix of brass strip, a pair of helixes of rods mounted about the helix of brass strip, axially oriented truss rods welded to the outside of the rod helixes and winding Wire helically wound about the truss rods. The winding wire is crimped to support the facing on outwardly projecting knuckles.

The present invention relates to an open face roll for a papermaking machine, and more particularly it relates to a novel winding wire for such a roll, said winding wire being comprised of a row of spaced, radially extending knuckles.

Perhaps the most commonly used papermaking machine roll that may be referred as an an open face roll, is the dandy roll of a Fourdrinier papermaking machine. The dandy roll is constructed of an open skeleton framework covered with a foraminous or reticulated facing, and the main structural element of the framework is an inner coil of a helically wound brass strip. A number of truss rods are helically wound parallel to each other and at a bias to the inner coil, and these are mounted through recessed grooves cut in the outer edge of the inner coil. Over the truss rods, a number of spaced, parallel top rods are mounted about the outer edge of the inner coil extending axially of the roll. A winding wire is helically wound through grooves in the outer surface of the top rods, and it directly supports the facing, which may be either a single, fine mesh, woven facing wire, or a coarse mesh backing wire covered with a fine mesh facing wire.

The dandy roll rides on the paper stock near the couch roll end of the wet part of the Fourdrinier machine to mat the stock into a paper web, and when desired, to imprint a watermark in the web. Although the dandy roll is often mounted between the last table roll and the couch roll, the paper stock must be quite wet when it moves under the dandy roll, if the dandy roll is to perform effectively. Suction boxes are located between the dandy roll and the couch roll to remove as much moisure as possible before the Web leaves the wet end of the machine so as to minimize the burden on the drier part of the machine.

A number of problems are encountered in the use of dandy rolls, and the severity of difiiculties caused by these problems often varies with the varying contents of the different paper stocks. The most common complaint is the tendency of the dandy roll to pick up and accumulate particles of stock which clog the interstices of the facing and accumulate on the side surfaces of the winding wire. If the dandy roll is not cleaned of these accretions, the web tends to stick to the dandy roll, leaving marks on the web in half-moon shape. To alleviate this problem, many mills spray water from needle jets under high pressure onto the dandy roll as a part of normal operation, but it is still necessary to clean the dandy rolls as frequently as once every two hours in some mills and less frequently in others. When the condition becomes too severe it is sometimes necessary to wash the roll in dilute sulphuric acid, a process called suoring, to clean it, and it is not uncommon to reface the roll before the old facing is worn out to avoid the greater expense of cleaning the roll.

Another problem sometimes occurs when the dandy roll, with its surface immersed in the stock, fails to release all of the moisture as it leaves the web. When this happens, short serpentine marks called worms form in the web as it leaves the nip of the dandy roll.

Water throw from the dandy roll inhibits the efficiency of the machine. If water drops thrown from the surface of the spinning dandy roll fall on a dry web, they will mark the web. To avoid this, the vacuum in the suction boxes is often reduced so that the water throw will fall harmlessly onto a wet web. Due to the proximity of the dandy roll to the end of the wet part of the machine, the drying of the web in the wet part can be seriously inhibited if the web must be allowed to remain wet for any great distance after it leaves the dandy roll. If the web is not sufiiciently dried before it leaves the wet part of the machine the added burden on the driers may require the whole machine to operate at a slower speed. On some machines making certain grades of paper, the dandy rolls of the prior art are known to carry water from the nip up to the apex of its rotation and throw the water backward into the web over the table rolls. Where this water throw becomes excessively heavy and forms large drops, marking of the web may result even though it is still very wet when the water throw strikes it.

Also, the winding wire of the prior art dandy rolls tends to leave parallel lines of transparency, similar to a watermark, in the paper. These lines may be avoided by using the backing wire fabric between the winding wire and the facing. However, the addition of the backing wire frequently interferes with drainage of water from the roll and it tends to entrap stock particles, creating or increasing the severity of a cleaning problem.

By utilizing a dandy roll embodying the present invention, these and other problems may be obviated altogether in many cases and substantially overcome in others. The present invention contemplates the use of a winding wire formed to project spaced knuckles in opposite directions in a radial plane relative to the roll so that both the lateral surfaces and the radial edges of the winding wire are interrupted or discontinuous. This is to be distinguished from the prior art winding .wire which has an elongated rectangular cross section and was mounted edgewise on the top rods to present continuous, narrow radially extending edges, and continuous, broad lateral surfaces. By the structure of the present invention drainage is improved, stock particle retention in the roll is very substantially reduced and marking of the web eliminated.

Although the embodiment of the invention here shown is a dandy roll, it is recognized that there are other types of open face rolls of similar structure and other types of papermaking machines which may utilize an open face roll of similar construction with the same problems of drainage and stock accumulation, but these rolls may not perform precisely the same step in the papermaking process as the dandy roll. For example, some types of Fourdrinier machines use dandy-type table rolls for which drainage and cleaning are significant considerations. Again, cylinder molds in cylinder machines are of similar construction, rely heavily upon their drainage capacity, and may present a very critical cleaning problem. However, to attempt here to describe each machine and each specific roll to which the present invention is pertinent would only unduly lengthen this disclosure and obscure the invention. Where an open face roll is used manifesting similar operating conditions, such as flow-through of the liquid phase of the pulp slurry, and analogous problems, such as accretion of stock particles and drainage capacity, those skilled in the art will perceive the utility and application of the present invention thereto. Therefore, it is stipulated that the references in this discussion to dandy rolls include such other open face paper machine rolls as are analogous thereto in structure and operating conditions and problems.

Accordingly, it is an object of the present invention to alleviate the need for cleaning open face paper machine rolls.

It is another object of the present invention to improve the drainage of open face paper machine rolls.

It is another object of the present invention to minimize water throw by open face paper machine rolls.

It is another object of the present invention to eliminate or reduce line marking on the paper web.

It is another object of the present invention to eliminate worm marks on the paper web from open face paper machine rolls.

It is another object of the present invention to increase the efiiciency of papermaking machines utilizing open face rolls.

It is another object of the present invention to permit the speed of a papermaking machine to be increased.

It is another object of the present invention to permit more efiicient removal of water from the paper stock.

It is another object of the present invention to obviate the need for a backing wire underlying the facing of an open face roll.

It is another object of the present invention to eliminate a tendency of the paper web to adhere to the surface of an open face roll and to eliminate thus the marking of the web resulting from its adherence to the roll surface.

It is another object of the present invention to provide a less expensive open face roll.

It is another object of the present invention to provide a low cost winding wire having discontinuous surfaces.

The foregoing and other objects will appear in the description to follow. In the description, reference is made to the accompanying drawing which forms a part hereof and in which there is shown by way of illustration a specific embodiment in which this invention may be practiced. This embodiment will be described in sufiicient detail to enable those skilled in the art to practice this invention, but it is to be understood that other embodiments of this invention may be used and that structural changes may be made in the embodiment described without departing from the scope of the invention. Consequently, the following detailed description is not to be taken in a limiting sense; instead, the scope of the present invention is best defined by the appended claims.

In the drawings:

FIG. 1 is a side view in elevation of a dandy roll embodying the present invention with successive portions broken away to illustrate its structure,

FIG. 2 is a view in section taken along line 2-2 in FIG. 1,

FIG. 3 shows an enlarged cross sectional segment of a dandy roll embodying the present invention, such as a portion of the whole cross section shown in FIG. 2.

In FIG. 1 successive layers of the structure of a dandy roll are shown. The outside dimensions of the dandy roll vary, of course, with the specifications of the machine it is used on. Its diameter may be as small as seven inches, or as large as or even greater than thirty-six inches. As a rule of thumb, so to speak, it has been found advisable, due to the problem of water throw from the dandy roll, to limit the rotational speed of the dandy roll to about 200 r.p.m., so on the faster machines, generally, a roll of larger diameter is used. Plainly, the length of the dandy roll must be equal to the width of the machine it is used on.

In the embodiment shown, trunnions 1 are fixed to each end to ride on trunnion bearings mounted on the sides of the paper-making machines. Shaft mounting is also used. The trunnions 1 are welded to an open, skeleton framework, the first inside element of which is an inner coil 2 that is made up of a helically wound, edgewise oriented brass strip. The brass strip of the inner coil 2 may be /2 to 1%; inches wide (radially) and to /8 inch thick (axially). Next are the truss rods 3, which are a number of parallel, helically wound rods ,43 to 0.156 inch in diameter, mounted through recessed grooves in the outside edge of the inner coil 2 and welded to the inner coil 2. As is evident in the drawing, the truss rods 3 are wound on a bias with respect to the inner coil 2.

Over the inner coil 2 and the truss rods 3 are a number of parallel, axially aligned top rods 4. The top rods 4 are equally spaced about the perimeter of the inner coil 2 and welded to both the inner coil 2 and the truss rods 3 at each cross point. In cross section the top rods may be either rectangular or circular, the latter being the more common, and the diameter of the top rods are commonly within a range of 4; inch to W of an inch.

The last outside element of the skeleton framework is a winding wire 5, which is helically wound about and mounted in grooves cut in the outside surface of the top rods 4. The winding wire 5 is radially crimped; that is, it is crimped in a radially extending plane so that inwardly projecting knuckles 6, facing the center of the dandy roll, and outwardly projecting knuckles 7 facing away from the center of the roll are formed. The frequency of the crimp should be such that the winding wire 5 rests on an inwardly projecting knuckles 6 on each top rod 4.

Although the preferred embodiment disclosed here shows winding wire 5 made up of a round wire crimped into a serpentine shape approaching the shape of a sinusoidal wave, this precise structure is not believed to be critical to the invention in its broadest aspects. The forces causing accumulation of paper stock in the roll, incomplete drainage, water throw and marking of the web have never been scientifically analyzed. However, it is believed that these problems are greatly affected by the intermolecular actions of the liquid phase of the stock manifested in such common phenomena as surface tension and capillary action. The prior art winding wire, with its elongated rectangular cross sectional shape, presented continuous outwardly and inwardly facing radial edges and uninterrupted broadside surfaces, which, when immersed in the wet stock, are believed to set up ideal conditions for the concentrated, deleterious operation of those forces to hinder the desired functioning of the dandy roll. Therefore, the present invention seeks to interrupt, if not eliminate, both the continuous outward facing edge and the continuous side surfaces of the winding wire. Whether or not the underlying hypotheses of the present invention are correct, the practical results achieved with application of the invention on production papermaking machines leave no doubt that the resulting structure of the invention provides substantial progress in the art of making such paper machine rolls. The significant structure appears to be the creation of alternately oppositely facing knuckles projecting or extending in a radial plane, whether these be achieved by crimping a wire, stamping sheet stock or some other means, and whether the shape of the knuckles be serpentine, rectangular, sawtooth, semicircular, or other similar shapes producing the desired knuckles to define interrupted side surfaces and edges. This shape, of course, achieves the same dimensional and stress resisting characteristics as the prior art winding wire. Hence, the term crimped may be considered to subsume this entire class of shapes without defining the process by which the shapes are achieved.

The structure of the winding wire 5 of the preferred embodiment has the particular advantage of achieving the desired result comparatively inexpensively in less than mass production quantities. The frequency of the crimp should be from 4 to 12 knuckles 6 or 7 per inch to accommodate the largest range of dandy roll sizes and structures. An amplitude of 0.085 inch is presently being used, but an amplitude range of 0.040 inch to /8 inch will achieve the desired spacing and mechanical strength for supporting the facing, and these are, after all, the primary functions of the winding wire 5. As this structure is applied to different rolls, such as cylinder molds or table rolls, the dimensions will vary accordingly.

To complete the dandy roll, a facing 8 is wrapped around the skeleton framework and is directly supported on the winding wire 5. The commonly used facing 8 is a woven wire fabric having a mesh count of 30 to 40, although facings may be found having a mesh count as high as 90 and as low as 20. At least 44% open area has been found to be desirable in a facing for dandy rolls. Hence, any foraminous or reticulated sheet having the desired uniformity of surface, mesh equivalent and open area may serve as a facing, whether it be of woven or perforate structure. In the prior art, a backing wire of much coarser weave or mesh Was placed between the winding wire 5 and the facing 8 to eliminate lines marked in the web by the winding Wire. However, the winding wire 5 of the present invention has obviated the need for the backing wire and to that extent has reduced the cost of dandy rolls and eliminated one structure which had aggravated the problem of accumulation of paper stock in the roll.

By means of the present invention, which is believed to effectively reduce the deleterious combination of intermolecular forces of the liquid in the roll, the retention of paper stock in the roll has been all but completely eliminated and drainage of liquid from the roll vastly improved. Hence, the expense and labor of cleaning such rolls are either eliminated or substantially reduced and the damage to the paper web from stock on the roll avoided. Also the marking of the web, which follows upon inadequate drainage, is eliminated. In addition, water throw from the roll is substantially reduced and this has several beneficial effects in a dandy roll. First, the reduced water throw permits drying of the web to be started closer to the roll so that a greater amount of moisture is removed from the web before it leaves the wet end of the machine. In any event, this increases the efliciency of the machine, and where the machine has had to be slowed due to the limited capacity of the driers, it may be accelerated to a faster speed. Also, in some cases, the reduced water throw may permit operation of dandy rolls at a higher r.p.rn., allowing machine speed to be increased without requiring an increase in the diameter of the dandy roll.

Corresponding advantages to those mentioned in relation to dandy rolls will accrue with the use of the present invention on other similar rolls, such as some table rolls, and on similar rolls in other types of machines, such as cylinder molds. Accordingly, the invention is not confined in its application to dandy rolls, and in its form to the specific embodiment disclosed, but is set forth in the following claims.

I claim:

1. A dandy roll comprising the combination of a cylindrical, helically wound inner coil having a trunnion secured at each end of the thus formed cylindrical helix;

a plurality of axially extending top rods secured at spaced intervals to the outside of said cylindrical helix;

a plurality of truss rods helically wound on said cylindrical helix between said inner coil and said truss rods;

a winding wire helically wound about said truss rods and fastened to said truss rods, said Winding wire being a crimped cylindrical wire having knuckles extending in a radial direction; and

a facing wire mounted around said winding Wire and supported on outwardly projecting knuckles of said winding wire.

References Cited UNITED STATES PATENTS 1,788,531 1/1931 Little 162-357X DONALL H. SYLVESTER, Primary Examiner.

A. C. HODGSON, Assistant Examiner.

US. Cl. X.R. 162-314 

